NEWARK — Officials are investigating a social media exchange that appears to be between an active-duty city police lieutenant and a retired city police officer in which Ras Baraka, the city's African-American mayor, is referred to as a gorilla .

Police officials said they obtained a screen shot of the Facebook conversation, which is being investigated as a violation of the department's social media policy. The screen shot was sent to Police Director Eugene Venable Wednesday, department spokesman Sgt. Ron Glover said.

Asked how the officials determined the page belongs to the lieutenant employed by Newark, Glover replied that the incident is under investigation. NJ Advance Media is withholding the names in the exchange because their roles in the incident could not be independently verified.

"What's particularly disturbing about this incident is that this police official has been on the job for many years and has some amount of influence over the rank and file in the department," Venable said.

The thread between the two writers opens with a picture of an ape captioned "Lmfao....How's your mayor?"

"Exactly!!!!" replies the writer believed to be the current police lieutenant.

In a subsequent reply, the same writer says "Bring back Sharpaaaa!!!!!", an apparent reference to former Mayor Sharpe James. He also says he is trying to "stay low" and that he had been transferred several times.

Multiple attempts by NJ Advance Media to reach the lieutenant and former lieutenant were unsuccessful. An officer at the precinct where the lieutenant had recently been assigned said Wednesday he is on sick leave.

"It's unfortunate that this happened and we will not tolerate an atmosphere of bigotry and intolerance anywhere in this Administration," Baraka said in a statement, adding that "I still believe we have the best police force in the State of New Jersey."

Venable said the department has instituted a strict social media policy in response to what he described as "scandalous" online commentary in the past.

"Anything on social media which could possibly be misconstrued and reflect negatively on the department is in violation," Venable said. The policy also prohibits police from posting crime-scene images, witness statements and other confidential material.

"The general order was created as the result of several embarrassing instances of online activity by members of the department that were quite racy and somewhat, quite frankly, borderline discriminatory...Violations of the order could result in disciplinary actions, including dismissal," Venable said.

The lieutenant believed to be involved in the online conversation remains on active duty pending an investigation into the exchange, Glover said. As of Thursday, the lieutenant had not been officially informed that an investigation had been initiated, Glover confirmed.

Capt. John Chrystal, president of the Newark Police Department Superior Officers' Association, said Thursday he was unaware of both the allegations against the lieutenant and the city's investigation.

Asked for comment on the investigation, Chrystal declined, citing a need to review the allegations first.